Apparatus for preventing oxidation in casting metals



Oct. 3,1944. .1. LANE I v 2,359,524

APPARATUS FOR PREVENTING OXIDATION IN CASTING METALS Filed May 8 1943 2 sheets-sheet 1 YfiM/K 30 7.. A

(QMPEESSOI? ATTORNEYS J. LANE Oct. 3, 1944.

APPARATUS FOR PREVENTING OXIDATION IN CASTING METALS Filed May 8, 1943 2 Sheets-Sheet 2 INVENTOR. J4me LANE, BY A? M ATTORNEYS Patented Oct. 3, 1944 APPARATUS FOR PREVENTING OXIDATION IN CASTING METALS Jack Lane, Alhambra, Calif., assignor to Ameri can Pipe & Steel Corporation,

Calif., a corporation of Nevada Alhambra,

Application May 8, 1943, Serial No. 486,246

Claims.

This invention relates to apparatus forcasting metals and relates particularly to the casting of metals which, when molten, are apt to be injuriously affected upon exposure to the .atmosphere.

Many metals, such as for example, magnesium and its alloys, are apt to be injuriously affected by oxidation when exposed in a molten condition to the atmosphere. Other metals of this character are aluminum and some'of its alloys. Still other metals when exposed to the atmosphere when in molten condition may be injuriously affected by the nitrogen present forming objectionable nitrides.

An object of the present invention is to provide apparatus for casting metals which may be injuriously affected when exposed in a molten condition to the atmosphere wherein the metal while in molten condition is adequately protectedby a gas which is-inert with the metal and wherein the metal is poured from the crucible into the mold cavity in the presence of such a gas whereby metal is adequately protected at all times from exposure to the air.

Still another object of the invention is to provide a relatively simple apparatus for casting metals that may be injuriously affected upon exposure to the atmosphere while in a molten condition so that wherein there is a crucible containing a supply of the molten metal, a conduit leadthat may be heated by any suitable source of heat, such as an oil burner l2. A stack l3 leads from the hearth and carries off the products of combustion that is utilized to heat the crucible In. This crucible is intended to receive and have melted therein a substance M which may be magnesium or its alloys, aluminum or its alloys, or any other substance that is apt to be injuriously affected when exposed to air.

The crucible I0 is equipped with a cover l5 to which leads a pipe or conduit Hi from a tank or reservoir 11 that contains a gas that is inert to the metal when the metal is in a molten state or which is otherwise suitable so that it will not injuriously affect it. The conduit I6 may be controlled by a valve l8.

l9 indicates a mold or chill in which there are one or more mold cavities 20. The mold is shown ashaving a cope 2| and a drag 22 separable upon a parting line 23. This mold is enclosed within a suitable cover or enclosure 24 which may or may not be separable at 25. A conduit 26 leads from the crucible to the gate 21 that supplies the ing therefrom to the mold cavity, with provision made for supplying a. gas that is inert to the metal to the top of the crucible cause it to flow therefrom through the conduit and through the mold cavity or cavities whereby the air that may be in the mold cavity and in the conduit is replaced by the inert gas and the gas which may have become heated from the molten metal may serve to preheat the conduit and the mold cavity I to prevent unnecessary chilling.

With the foregoing and other objects in view, which will be made manifest in the following detailed description and specifically pointed out in the appended claims, reference is bad to the accompanying drawings for an illustrative embodi- 'ment of the invention, wherein:

mold cavities 20. The mold cavities are provided with vents indicated at 28 and these vents may be conventional risers. A conduit 29 leads from the enclosure 24 back to the tank or reservoir l1 and in this conduit there may be a compressor 30. Any type of casting apparatus may be employed in lieu of the mold [9. The only essential characteristics of the casting apparatus are that some means be provided for venting the mold cavities and if the gas utilized in tank I! is either a noxious gas or one which is expensive so that it is desired to retain or preserve it or reuse it where possible, then the mold should be enclosed in an enclosure 24 and the conduit 29 and compressor 30 be employed to preserve and return the gas to the tank I! for reuse.

A centrifugal casting apparatus may be employed in lieu of the mold IS in which case-the gate of the casting apparatus should be arranged coincident with the axis of rotation and have the conduit 26 lead thereto.

brought up to a molten condition suitable for casting, During this operation valve l8 may be.

opened to allow the inert gas in the tank or res-- ervoir H to flow therefrom into the crucible through pipe Hi. This expels and replaces the air that will be initially in the crucible and causes the air to flow outwardly therefrom through the conduit 26 into gate 21, outwardly through runners that may lead from the gate to' the mold cavities, through the mold cavities, and out of the vent or vents 28. This air that is initially expelled may be released from the system by means of a three-way valve 32 that may be incorporated in conduit 29. When the air has been thus expelled the valve 33 may be turned so as to close the outlet '34 and gas from the tank or reservoir I! will then follow the same path through the crucible, conduit 25, and through the mold. This gas, which is present in the crucible and which is inert to the molten metal or which will at least not injuriously affect it, serves to protect the metal as it is brought up to a casting heat. It may also be heated by the crucible and serve to warm the conduit 26 and the mold so that there will be no unnecessary chilling at the time of casting. When the metal vis ready for casting, rock shaft 32 is rotated to swing the dipper 3| into the elevated position illustrated in dotted lines in Fig. 1. The dipper elevates a supply of the molten metal and allows it to flow downwardly through conduit 25 and into the gate 21. The gas which may be in conduit 26 in the gate 21 and in the mold cavities may be freely expelled ahead of the molten metal through the vents or risers 28.

During this casting operation it will be appreciated that the metal is maintained at all times out of contact with the air so that it will not be oxidized or otherwise injuriously afiected. When the metal has solidified in the mold the enclosure 24 may be opened or removed, the mold opened and the casting or castings recovered. If the inert gas is not noxious or expensive the return afforded by conduit 29 and compressor 30 may be dispensed with and the gas allowed to freely escape through the vents or risers 28. If the gas is expensive or noxious it may be conducted off through conduit 29, compressed by compressor 30 and returned to tank H for reuse. The inert gas employed will vary with various metals and compositions. It is preferable, however, that the gas be relatively heavy, such as for example, carbon dioxide. Other gases such as carbon monoxide, nitrogen, or sulphur dioxide may be employed.

In Fig. 2 an alternative form of construction is disclosed wherein the crucible is indicated at mounted on a hearth 5| and heated such as by an oil burner 52. 53 indicates the stack leading from the hearth and 54 the cover for the crucible. The tank for the inert gas is indicated at 55 and a pipe 56 leads therefrom to the crucible. In this instance the outlet from the crucible is provided by the conduit 51 which communicates with the interior of the-crucible at a point slightly. above the bottom thereof. This outlet from the crucible formed by the conduit 51 is controlled by means of a valve 58 operable by handle 58 from the exterior of the crucible.

A branch conduit 60 leads from the pipe 56 through a valve 6| to conduit 51. Conduit 51 leads to the gate 62 in the cope 63. This gate is connected by runners 64 to the mold cavities 65 which are vented as at 66.

To illustrate the application of the invention to another type of casting apparatus differing from that illustrated in Fig. 1, the drag 61 of the mold shown is supported on a vertical shaft 68 of a hydraulically or pneumatically operable piston 69. It is slidable on standards 10. The mold is disposed within a receptacle or enclosure having a top 1| supported on the standards and a bottom" that is likewise supported on the standards. The side walls which may or may not be cylindrical and which are indicated at 13 may be raised and lowered by means of piston rods 14 of pistons disposed in hydraulic or pneumatic cylinders 15.

In this form of construction the molten metal 16 is protected from injurious eil'ects of the atmosphere by the inert gas that is supplied from the tank or reservoir 55. When the metal is brought up to casting heat valve 6| may be opened to allow some of the inert gas to flow through the bottom of conduit 51 and out through'the mold cavities and through the vents, thus replacing the air that is initially present in conduit 51 and in the mold cavities. When the air has been thus replaced by the inert gas the valve 58 may be opened and the required amount of metal allowed to flow through conduit 51 into the gate 62 to fill the mold cavities. When the metal in the cavities has solidified the wall 13' It will be appreciated that either type of crucible may be employed with either type of casting apparatus and that the mold or casting machine need not conform to either of the casting machines illustrated. In the form illustrated in Fig. 2, the outlet from the crucible is preferably arranged above the bottom of the crucible so that impurities that may be present in the metal and which tend to settle may collect in the .bottom of the crucible and will not flow with the molten metal to the mold cavities.

From the above-described constructions it will be appreciated that I have devised a method and apparatus wherein metals that may be injuriously affected by exposure to the atmosphere are adequately protected both while in the crucible itself and during the casting operation.

Various changes may be made in the details of construction without departingfrom the spirit or scope of the invention as defined by the appended claims.

I claim:

1. In combination, a mold having a mold cavity, a gate and a vent arranged so that flow from the gate is through at least a portion of the mold cavity to the vent, a crucible, a conduit closed against ingress of air leading from the crucible to the gate, means for introducing a gas inert to the material to be cast into the conduit to pass therethrough through the gate, mold cavity, and vent to wash air therefrom, and means for flowing the material to be cast from the crucible through said conduit and gate into the mold cavity.

2. In combination, a mold having a mold cavity, a gate and a vent arranged so that flow from the gate is through at least a portion of the mold cavity to the vent. a crucible, a conduit closed against ingress of air leading from the crucible to the gate, means for introducing a gas inert to the material to be cast into the conduit to assua e pass therethrough, through the gate, mold cavity, and vent to wash air therefrom, means'ior flowing the material to be cast from the crucible through said conduit and gate into the mold cavity, and means for recovering the gas expelled from the vent and subsequently returning it to the conduit.

3. In combination, a mold having a mold cav-- ity, a gate and a vent arranged so that iiow from the gate is through atv least a portion of the mold cavity to the vent, a crucible closed against ingress of air, a conduit closed against ingress of air leading from the crucible to the gate, means 'ior introducing a gas inert to the material to be cast into the conduit to pass therethrough, through the gate, the mold cavity, and vent to wash air therefrom, and means ior flowing the material to be cast from the crucible through said conduit and gate into the mold cavity.

a. In combination, a mold having a mold cavity, a gate and a vent arranged so that flow from the gate is through at least a portion of the mold cavity to the vent, a crucible, a conduit closed against ingress of air leading from the crucible to the gate, means for introducing a gas inert to the material to be cast into the conduit to pass therethrough, through the gate, mold cavity, and vent to Wash air therefrom, means for flowing the material to be cast from the crucible through said conduit and gate into the mold cavity, and means for recovering the gas expelled from the vent and subsequently returning it to the conduit.

5. In combination, a mold having a mold cavity, a gate, and a vent arranged so that flow from the gate is through at least a portion of the mold cavity to the vent, a crucible closed against ingress of air, a conduit closed against ingress of air leading from the crucible to the gate, means for introducing a gas inert to the material to be cast into the crucible so as to maintain the material therein in an inert atmosphere and to flow therefrom through the conduit, gate, mold cavity, and vent to expel air therefrom, and means for flowing material to be cast through'the conduit and gate into the mold cavity.

5. In combination, a mold having a mold cavity, a gate, and a vent arranged so that flow from the gate is through at least a portion of themold cavity to the vent, a crucible closed against ingress of air, a conduit closed against ingress of air leading from the crucible to the gate, means for introducing a gas inert to the material to be cast into the crucible so as to maintain the material therein in an inert atmosphere and to how therefrom through the conduit, gate, mold cavity, and vent to expel air therefrom, means for flowing material to be'cast through the conduit and gate into the mold cavity, and means for recovering the gas expelled from the vent and subsequently returning it to the crucible.

7. In combination, a centrifugal mold having a gate, a mold cavity and a vent from the mold cavity arranged so that flow from the gate is through the mold cavity to the vent, a crucible, means for maintaining the material in the crucible to be cast under an inert atmosphere, a conduit closed against ingress of air leading from the crucible to the gate, means for introducing a gas inert to the material to be cast into the conduit to expel air therefrom through the gate, mold cavity, and vent, and meansfor flowing the material to be cast through the-conduit and gate into the mold cavity.

8. In combination, a centrifugal mold having a gate, a mold cavity and a vent from the mold cavity arranged so that flow from the gate is through themcld cavity to the vent, a crucible, means for maintaining the material in the crucible to be cast under an inert atmosphere, a conduit closed against ingress of air leading from the crucible to the gate, means for introducing a gas inert to the material to be cast into the conduit to expel air therefrom through the gate, mold cavity and vent, means for flowing the material to be east through the conduit and gate into the mold cavity, and means for recovering the gas expelled from the vent and subsequently returning it to the conduit.

9. in combination, a centrifugal mold having a gate, a mold cavity, and a. vent from the mold cavity arranged so that flow is from the gate through the 'mold cavity to the vent, a crucible closed against ingress of air, a conduit closed against ingress of air leading from the crucible to the gate, means for introducing a gas'inert to the material to be cast into the crucible to now therefrom through the conduit, gate, and

mold cavity to expel air therefrom, and means for flowing the material to be cast from the crucible through the conduit and gate into the mold cavity.

10, In combination, a centrifugal mold having a gate, a mold cavity, and a vent from the mold cavity arranged so that flow is from the gate through the mold cavity to the vent, a crucible closed against ingress of air. a conduit closed against ingress of air leading from the crucible to the gate, means for introducing a gas inert to the material to be cast into the crucible to flow therefrom through the conduit, gate, and mold cavity to expel air therefrom, means for flowing the material to be cast from the crucible through the conduit and gate into the mold cavity, and means for recovering the gas expelled through the vent and subsequently returning it to the crucible.

JACK LANE. 

